Estee



UNITED STATES PATENT OFFICE.

HIRAM J. DREHER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO HIMSELF, GEORGE M. WETMORE, AND CHARLES H. ANGEL, OF ROCH- ESTER, NEW YORK.

PROCESS OF SEPARATING PLUMBAGO FROM'ITS ORES.

SPECIFICATION forming part of Letters Patent No. 235,858, dated December 28, 1880,

Application filed March 25, 1880. (Specimens) To all whom it may concern:

Be it known that I, HIRAM J. DREHER, of Philadelphia, Pennsylvania, have invented an Improved Process of Separating Plnmbago from its Ores, of which the following is a specification My invention relates to an improved process of separating plumbago or black lead from the minerals with which it is associated in nature by disintegrating the ores by the combined action of heat and water, and then reducing the calcined and disintegrated ore by crushing and rolling, after which the material thus treated is then separated and ground in 1 a mill and bolted to obtain the puritied plumbago.

Graphite or plumbago usually occurs in na ture in flakes of varying sizes disseminated through a hard ore consisting of silica, iron,

and other impurities, from which it is difficult of separation by any known process.

In the practical operation of my improved process of separating plumbago from its ores I calcine or roast the ore in any ordinary roasting-furnace, and withdraw the ore from the furnace while hot, and either immediately immerse. it in water or throw water on it to efiect its disintegration. The plumbago is but little affected by the heat, and while the hard 0 portions of the ore are rendered friable by this treatment, the flakes retain their original size and shape. I prefer in this step of my process to throw water onto the heated ore, as in this way a less quantity of water is needed,

. 3 5 and the ore becomes dry spontaneously before the subsequent operations are commenced. The calcined and disintegrated material is now passed through a rotary crusher or other comminuting apparatus, by which it is reduced to l 0 a coarse powder. The ore is then fed through one or more sets of crushing-rollers, by which it is still further reduced in size, while the flakes are flattened out, separated from each other and from any adhering particles of iron. After passing through the rollers the material 5 is next passed to a separator, which maybe of any usual form of construction, and by which the flakes are separated from the powdered ore. The ore passes through the sieve, while the flakes go over the tail, or they may be graded into different grades by using sieves of varying mesh at the lower end of the separator. The plumbago, now obtained in flakes of varying size and almost entirely freed from the ore, is ground between millstones, by which treatment it is reduced to powder, and it is then bolted into different qualities by being passed successively through ordinary revolving bolts clothed with cloth of different mesh.

By my improved process I am enabled to obtain a largely-increased yield of plumbago from any given ore, and the plumbago thus obtained is of a superior quality.

I claim 1. The herein-described process of separating plumbago from its ores, consisting in disintegrating the ore by the combined action of heat and water, crushing and rolling the disintegrated material, and separating the flakes from the ore, substantially as described.

2. The herein-described process of separating plumbago from its ores, consisting in disintegrating the ore by the combined action of heat and water, crushing and rolling the disintegrated material, separating the flakes from the ore, and subsequently grinding and bolting the flakes, substantially as described.

H. J. DREHER.

Witnesses PETER A. BEAVER, Gno. M. WETMORE. 

